LIME. 



the moss late in the autumn, five lines 

 long ; body glossy, with undulate, trans- 

 verse striae on the shield; narrower and 

 not so much wrinkled as the next. L. 

 ater; body black and furrowed with deep 

 wrinkles ; of this species there are five or 

 six varieties, differing' in colour and size ; 

 the dusky -brown with a yellowish mouth, 

 a streak on each side ; is found in woods, 

 meadows, fields, and gardens ; is from one 

 and a half to five inches long; crawls 

 slowly, and leaves a slime upon whatever 

 it passes over. L. alba, is white, and is 

 found in woods and groves; from three 

 to five inches long. L. hyalinus ; body 

 hyaline ; feelers obsolete, with a brown 

 line reaching from the feelers to the 

 shield ; inhabits mossy places, and is very 

 destructive to the young shoots of kid- 

 ney-beans ; belly with numerous inter- 

 rupted wrinkles. L. agrestes ; body 

 whitish, with black feelers: five varie- 

 ties, of which some have the power of 

 secreting a large quantity of mucous from 

 the under surface, and forming it into a 

 thread like a spider's web ; by this means 

 it often suspends itself, and descends 

 from the branches of trees, or any height 

 it had crawled up to. It is found in Eng- 

 land, in gardens, pastures, and groves, 

 from May till December. One of the va- 

 rieties of this species is that which has 

 been recommended to be swallowed by 

 consumptive persons ; it is half an inch 

 long, and when touched it sticks as if dead 

 to the fingers. 



LIME, or calcareous earth, predomi- 

 nates in most stones which are soft 

 enough to be scratched with a knife. 

 These are chalk, lime-stone, marble, 

 spars, gypsum, or plaster-stone, and va- 

 rious others. As the lime is most fre- 

 quently combined with carbonic acid, it 

 is usuul for mineralogists to drop a small 

 quantity of nitric acid upon the stones 

 they are desirous of classing; and if they 

 froth by the escape of the acid, they con- 

 clude that lime enters into the composi- 

 tion. To obtain pure calcareous earth, 

 powdered chalk must be repeatedly boil- 

 ed in water, which will deprive it of the 

 saline impurities it frequently contains. 

 It must then be dissolved in distilled vine- 

 gar, and precipitated by the addition of 

 concrete volatile alkali. The precipi- 

 tate, when _ well washed and dried, will 

 consist of lime united to carbonic acid ; 

 the latter of which may be driven off' by 

 heat, if necessary. 



If chalk, marble, lime-stone, spar, or 

 any other specimens of this earth, con- 

 taining carbonic acid, be exposed to con- 



VOL. IV. 



tinned ignition, they give out carbonic 

 acid and water, to the amount of nearly 

 half their weight. The remainder, con- 

 sisting chiefly of lime, has a strong ten- 

 dency to combination, and attracts water 

 very powerfully. The addition of water 

 to lime produces a very considerable 

 heat, attended with noise, and agitation 

 of the parts, which break asunder ; a con- 

 siderable vapour arises, which carries up 

 with it part of the lime; and a phosphoric 

 light is seen, if the experiment be made 

 in the dark. Lime thus saturated with 

 water is said to be slaked. Water dis- 

 solves about one five-hundredth part cf 

 its weight of lime, and is then called 

 lime-water. This solution has an acrid 

 taste, and turns syrup of violets to a green 

 colour. If lime-water be exposed to the 

 open air, the lime attracts carbonic acid, 

 and is by this means converted into 

 chalk ; which, not being soluble in water, 

 forms a crust on the surface, formerly 

 called cream of lime, which, when of a 

 certain thickness, breaks, and falls to the- 

 bottom : and in this way the whole of the 

 lime will in time be separated. If the 

 fire have been too violent in the burning 

 of lime, the stones become hard, sono- 

 rous, and incapable of absorbing water 

 with the requisite degree of avidity. This 

 effect seems to arise from part of the cal- 

 careous earth having entered into fusion, 

 with the clay, flint, or other contaminat- 

 ing; earths, with which it forms a glass 

 that covers and defends the rest. 



The paste of lirne and water, called 

 mortar, has a degree of adhesion and duc- 

 tility, though much less than clay. When 

 dry, it is more or less friable, like chalk. 

 A mixture of sand, or broken earthen 

 vessels, greatly increases its firmness, 

 which it seems to effect by rendering it 

 more difficult for the parts to be remov- 

 ed with respect to each other. When 

 mortar is left to dry by the gradual eva- 

 poration of its superfluous water, it is 

 very long- before it obtains its utmost de- 

 gree of firmness. But if dry quick- lime 

 be mixed with mortar, it gradually ab- 

 sorbs the superfluous water, and the mass 

 becomes solid in a very short time. See 

 MORTAR. 



Lime has an affinity for tannin, whence 

 it is probable that a portion of it is retain- 

 ed in tanned leather, perhaps not to the. 

 improvement of its quality. It has an 

 edulcorative power with respect to ani- 

 mal oils, by combining with the putrid 

 gelatine in them ; but its action on them 

 in forming a soap is too strong to nclmit 

 of its being used for this purpose with ad- 



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